1. Field of the Invention
The present invention relates to a display control apparatus for controlling display responsive to touch input, a display control method, and a storage medium, and in particular, to a display control apparatus that corrects for a deviation between an input position (input coordinates) and a display position (that is, coordinates) of touch input, a display control method, and a computer-readable storage medium storing a program for causing a computer to implement the method.
2. Description of the Related Art
In general, there are known electronic devices or systems which produce displays using an input means such as a touch panel. Also, user interfaces using an application that enables intuitive input operations through touch input from a touch panel or the like have been developed.
In such electronic devices using touch input from a touch panel or the like, a deviation between target coordinates on a display screen and detected coordinates when touch input is done correctly at the target coordinates (a coordinate deviation) occurs due to factors such as user's parallax or age deterioration.
To correct for such a coordinate deviation, the electronic devices or the like are equipped with a so-called calibration menu (hereinafter also referred to as the calibrating function). Users can correct for a coordinate deviation using the calibration menu.
However, in a case where the calibrating function is used, when a user makes an error in a calibrating operation, it may be impossible to accurately operate the device through touch input.
To prevent such an inconvenience, for example, it has been known that calibration results are checked (see, for example, Japanese Laid-Open Patent Publication (Kokai) No. H10-116155).
According to Japanese Laid-Open Patent Publication (Kokai) No. H10-116155, the center of a display screen is displayed as a contact position. Then, when a user issues an instruction by touching a touch panel in accordance with the contact position, physical coordinate data is output. It is determined whether or not logical coordinate data obtained by coordinate transformation of the physical coordinate data based on new reference positional data lies inside an allowable range. When it is determined that the logical coordinate data lies outside the allowable range, calibration is performed again.
According to the method described in Japanese Laid-Open Patent Publication (Kokai) No. H10-116155, calibration results are checked, but when a user makes an error in calibrating operation, it is extremely difficult to know when the error occurred. Also, according to Japanese Laid-Open Patent Publication (Kokai) No. H10-116155, it is necessary to perform calibration again from the beginning.
On the other hand, there has been known a method that limits an area where touch input is allowed, and determines that touch input outside the area is ineffective during touch input for calibration. According to this method, touch input determined to be ineffective is not used for calibration, and this can prevent user's erroneous operations.
According to the above method, an area where touch input is allowed is limited to a range of coordinate deviation assumed to occur in normal use (a limited range) before product shipment. Thus, touch input assumed to deviate from target coordinates of calibration caused by a user's erroneous operation, not by an error resulting from a coordinate deviation, can be excluded.
However, a coordinate deviation beyond the limited range of coordinate deviation assumed to occur in normal use may occur in a hostile environment such as exposure to high temperature for a long time (hereafter referred to as an extreme environment). In such cases, even when a user performs a normal calibrating operation, this cannot be recognized as touch input inside the limited range.
Thus, when a coordinate deviation beyond the limited range occurs, it is possible that calibration cannot be performed even when a user performs a normal calibrating operation (that is, even when a user makes no error).